Q. Verizon Wireless sent me a notice that it’s going to combine its advertising system with AOL’s. How much more closely can they track me?

A. Unless you’ve gone out of your way to opt out of Verizon’s “Relevant Mobile Advertising” program, the nation’s largest wireless carrier already knows an extraordinary amount about your online habits.

But if you’ve spent time at AOL’s network of sites -- including such popular destinations as the Huffington Post -- Verizon can soon learn even more about your interests even as it scales back “RMA” tracking.

A second Verizon advertising program, “Verizon Selects,” may be less of a worry. This is an opt-in proposition--if you’ve never heard of Selects, you almost certainly didn’t sign up--that offers participants a small incentive, in the form of extra points in Verizon’s “Smart Rewards” rebate program, instead of just closer-targeted ads.

But at the same time, Verizon says it will cut back on its UIDH tracking. Instead of attaching this beacon to all of your unencrypted traffic, it will only add it to data sent to Verizon and AOL sites, as well as designated “partner sites” that help Verizon and AOL provide service there. I found the clearest explanation of that not at Verizon’s privacy notice, but in a post on its public-policy blog.

That notice also says Verizon will move other customer data, including your street and e-mail address, into AOL’s existing ad network.

Verizon describes this as merely a better-focused version of the traditional online ad proposition: Advertisers tell us what kind of customers they want to have see their ads, and we’ll use our customer data to show it only to those people. It should not have ads dumped in your e-mail inbox or precision-targeted to VzW subscribers on your street.

“For example, an advertiser wants to reach females, over 40, who live in a specific town,” said Verizon spokesman David Samberg. “We provide the advertiser with the ability to have its ad served to people who are part of the group they want to address.”

The simplest way to check for any you might have shared with the world years ago, intentionally or not, is to use Facebook’s option to show your profile as strangers see it. Go to your profile in a desktop browser, click the ellipsis icon below your header photo, and click “View As…” to see how the public sees it.